Technical Field
The disclosure is related to liquid crystal display technology field, and more particular to a liquid crystal display device and a driving method thereof.
Related Art
The evolution of photoelectric and semiconductor technology has also led to the flat panel display to flourish. Among the various flat panel displays, the liquid crystal display device (referred to as LCD) has become the mainstream product on the market because of many superior characteristics of high space utilization efficiency, low power consumption, no radiation, and low electromagnetic interference.
The LCD device generally includes a liquid crystal display panel and a back light module (referred to as BL). Because the liquid crystal display panel itself does not have the self-luminous characteristics, the backlight module must be configured under the liquid crystal display panel to provide a surface light source to the liquid crystal display panel, so the liquid crystal display panel may display the image through the surface light source provided by the back light module.
In the liquid crystal display device, each of the liquid crystal cells corresponds to a thin film transistor (abbreviated as TFT). The TFT can be controlled to switch each of liquid crystal cells, i.e., each of TFTs should be understood as a valve. The valve can be switched to control the level of brightness and darkness of the corresponding pixel cells. When the valve is open, the light may pass through the valve, and the bright pixel cells may be obtained; when the valve is close, the light may not pass through the valve, and the dark pixel cells may be obtained. Besides the switch function of the valve, the switching extent of the valve may also be controlled by the magnitude of the applied voltage. The grade of the light emitting strength of the pixel cells are controlled in accordance with the backlight strength to achieve the purpose of grayscale controlled by class.
The brightness and the penetration of the liquid crystal display device exist a certain relationship, and the penetration is related to the voltage applied on the pixel. Therefore, the brightness of the liquid crystal display device is related to the voltage on each of the pixels. Usually, the relationship between the voltage and the penetration may be shown by using the gamma curve.
In current technique, the gamma voltages are usually divided to two groups based on the common voltage VCOM, wherein the voltage greater than the common voltage VCOM is defined as the positive gamma voltage group, and the voltage smaller than the common voltage VCOM is defined as the negative gamma voltage group. The grayscales displayed on the liquid crystal display device are the same by using the two groups of gamma voltages symmetrized in the common voltage. FIG. 1 is a schematic view of the liquid crystal display device of the current technique. Refer to FIG. 1, when the liquid crystal display device of the current techniques displays an image, a gamma generator 150 generates the positive gamma voltages and the negative gamma voltages, and all of the positive gamma voltages and the negative gamma voltages are supplied to the data driver (Source IC) 120. The data driver 120 selects the corresponding gamma voltage from the positive gamma voltages and the negative gamma voltages provided by the gamma generator 150 according to a polarity inversion (POL) signal provided by the timing controller 110. Then the data analog voltages are gamma corrected by the selected gamma voltages, and then the gamma corrected data analog voltages are provided to the liquid crystal display panel 140. The data analog voltages are transformed from video digital signals (i.e. the data signal as shown in FIG. 1) received by the data driver 120 from the timing controller 110.
In order to transmit all the gamma voltages to the data driver 120, there are more traces connected to the data driver 120. For example, the group of positive gamma voltages includes ten positive gamma voltages and the group of negative gamma voltages includes ten negative gamma voltages. Thus the gamma driver 120 at least need twenty pins for the memory select pins, and the traces connected to the data driver 120 at least need twenty. Therefore, the driving structure is complex, the wiring area on the liquid crystal display panel is increased, and it is unfavorable for narrow frame design of the liquid crystal display device. Further more traces result in increase on the cost.